The invention relates to a method of and to an apparatus for converting webs of paper or the like into a series of stacks with coherent sheets or panels in zig-zag formations. More particularly, the invention relates to improvements in methods of and in apparatus for converting a continuous web of paper or the like into a succession of coherent panels which are bounded by transversely extending weakened portions of the web, and for thereupon transforming such succession of coherent panels into a series of discrete stacks of superimposed panels in zig-zag formations.
The manner in which a web of paper or the like can be converted into a succession of coherent panels with transversely extending weakened portions (such as rows of perforations) between neighboring panels is fully disclosed in commonly owned U.S. Pat. No. 4,708,332 granted Nov. 24, 1987 to Besemann for "Method and apparatus for zig-zag folding webs of paper or the like". Commonly owned copending patent application Ser. No. 268,472 filed Nov. 7, 1988 by Peter et al. discloses a method of and an apparatus for subdividing a continuous web into a series of shorter webs and for spacing apart successive shorter webs for the purpose of facilitating conversion of successive shorter webs into discrete stacks of overlapping panels in zig-zag formations.
A drawback of presently known apparatus for gathering stacks of superimposed panels in zig-zag formations is that the stacks tend to lean forwardly or backwards (as considered in the direction of transport of a continuous web and of shorter webs through the apparatus). In other words, certain stacks fail to assume a predetermined shape which is best suited for introduction into boxes or like receptacles. Departure of the shape of certain stacks from a truly parallelepiped shape creates problems during boxing or crating of forwardly or rearwardly leaning stacks. Typical examples of stacks which are obtained by zig-zag folding predetermined numbers of panels consisting of paper or the like and being connected to each other by transversely extending weakened portions (which normally contain rows of perforations) are stacks of so-called computer paper which is provided with marginal and other perforations for convenience of manipulation in a computer and/or upon removal from the computer. Failure of a single stack of a long series of stacks to enter a box or a like receptacle is likely to necessitate a shutdown of the entire production line with attendant huge losses in output.